Arterial Wall Shear and Distribution of Early Atheroma in Man

Abstract

THE patchy distribution of fatty streaking and early atheroma has been associated with arterial blood mechanics. Mustard et al.¹ have noted occurrence of atheroma at sites which are thought to experience particle (platelet) deposition as the result of local rapid flow fluctuations (turbulence) or eddies. Others have proposed platelet deposition in regions of flow separation². Texon³ invoked damage due to Bernoulli-type suction forces in areas of locally increased blood velocity; but this is considered implausible because the forces are negligible in physiological conditions in comparison with normal variations of mean blood pressure. Mitchell and Schwartz⁴ reported the sparing of fatty streaking in localized areas, at which they suggest low wall shear rate (the product of velocity gradient and fluid viscosity) is experienced. Fry^5,6 has shown that acute elevation of shear rate on the aortic wall causes endothelial damage and increased permeability to lipids. These theories assign to fluid mechanics a causative role in atherogenesis.